Antenna system



June 29, 1948. o w o w JR 4 2,444,320

ANTENNA SYSTEM Filed Aug. 10, 1944 IN V EN TOR.

147 TOW/V5) Patented June 29, 1948 ANTENNA SYSTEM Oakley M. Woodward,Jr., Princeton, N. J., assignor to Radio Corporation of America, acorporation of Delaware Application August 10, 1944 Serial No. 548,817

This invention relates to radio antennas, and more particularly toantenna systems for pro viding horizontal uniform omnidirectional fieldpatterns, with predetermined vertical directivity and uniformpolarization.

The principal object of the present invention is to provide an improvedtype of antenna system which may be designed to provide a field patternwhich is substantially uniform horizontally.

Another object is to provide a system of the described type which willradiate and respond to substantially only horizontally polarized energy.

A further object of the invention is to provide a system of thedescribed type whichmay be designed to provide any desired degree ofelevational directivity. I

A still further object is to provide an antenna system of relativelysimple construction which may be designed readily to exhibit therequired characteristics of uniform horizontal directivity andhorizontal polarization. 1

These and other objects will become apparent to those skilled in the artupon consideration the accompanying drawing, of which a Figure 1 is aschematic plan view of a prior art antenna of the general type to whichthis invention relates,

Figure 2 is an elevation of the antenna of Figure 1,

Figure 3 is a schematic plan view of an antenna constructed inaccordance with the present invention,

Referring to Figures 1 and 2, a typical prior art antenna for providinghorizontal polarization comprises a plurality of stacked layers l, 2, 3and 4, each comprising four horizontal dipoles 5, 6, l and 8 spaceduniformly around a cylindrical conductive support 9. Although thedipoles 5, 6,

l and 8 are represented by single lines, it is to be understood thateach includes a pair'of 001-' linear conductors disposed end to end withthe adjacent ends connected to the respective terminals of atransmission line, as described below with reference to Figure 6. It issufiicient for the present to say that the radiators are all connectedeffectively in parallel to operatein phase,

so that the currents all flow in the same direction simultaneously, thatis all clockwise or all counter-clockwise if viewed from the top, asindi- 11 Claims. (Cl. 250-3353) cated by the arrows in Figure 1. Thelayers I, 2, 3and 4 are spaced vertically along the support 9 atintervals of one-half wavelength. The elevationaldirectivity of thesystem is determined in accordance .with principles well known to thoseskilled in the art, by the number-of such layers. Each of the dipolesisspaced one-quarter wavelength radially from the surface of the support9.

The field intensity in a-horizontal plane produced by theabove-described antenna with a current I in each of the radiatorelements is 26 of the following description, with reference to i where kis a constant, W0, W4, W8,

The corresponding horizontal directive pattern of the antenna of Figure1 is illustrated by the curve designated E on the polar graph of Figure5. The maximum field intensity is arbitrarily designated as F. Itisevident that the field is not uniform, but varies approximately 30percent, from .707 F to 1 F.

The principle of the instant invention lies in superimposing upon thepattern of Figure 5 a similar pattern, displaced at an angleof 45 withrespect thereto. Referring to Figures 3 and 4, an array constructed inaccordance with the present invention comprises layers W, H, l2, l3 ofradiators similar to the layers l, 2, 3 and 4 of Figure 2, withsuccessive layers displaced horizontally through an angle of 45. Thusthe radiators of the layer ID are parallel to the respectivecorresponding radiators of the layer l2, and at an angle of 45 to therespective corresponding radiators "of the layers ll and i3. As in thesystem of Figures 1 and 2, all of theradiators are operated in phase.With a current I flowing in each radiator, the field intensity in ahorizontal plane produced bythe layers In and I2 is (a =:EW

It is apparent that Er is independent of the angle" and is thereforehorizontally uniform. Any number of pairs of layers similar tothepairslllfi II and I2, I3 may be employed to provide any. desireddegree of vertical directivity.

Referring to Figure 6, a preferred mechanical structure of the radiatorelements is illustrated} The supporting conductor 9 is provided with aplurality of holes m which short' cylindrical sleeves M are secured,extending radiallyoutsleeves l4 are adaptedto receive with a press fittubular members I5} Each'of the members I5 is provided. with'asho'ulderl6 *for' engagement with the outer end of the sleeve l4, "and carry atits outer end'a pai1""of "c0llinearconductors I] and I8; A'pair'of slots'19 areformed in the" member l5, extending radially inward toward theshoulder l6 forming a slot of a length hereinafter specified, The slotsI!) lie in a plane at right'angles to themeinbe'rs I! and 18." A conductor 2| issupported :coaxi'ally within the mem ber l5 by an insulat'or22, and terminates at its:- inner end near 'the'surfacebf aconductor'23.'? A conductor 23" is supported coaxially Within theconductor The outer endof the conductor Zlf is bent at right angles andconnected to the main-- ber l5 atits outeren-d at the pointz l.

Figure 6 shows 'only'a'portion'of a'singlelayer of radiator elements.The remainder of the elements of this layer, as well as those of theother layers, are identical in "construction'with those which areillustrated. l-loweven: the'dipolesof each layer are physically reversedin position: with respect to-tho se of the, adjacent layers, in order toprovide inphase excitation of all ofthe dipoles-with one-half wavespacing: between ad jacent layers. a The instant invention is not lim;ited to a specific dipole structura'which is illus trated-merely to showone embodiment thereof.'

The. lower ends of the conductors 9 and 23 may be connected to 'atranslation device such as [a 1 radio receiver or transmitter. The.inner con. ductor 23' is coupled to the conductors 2|. by virtue of thecapacitance existing between the inner; ends of the conductors 2i andthe surface of the} conductor 23. Assuming a voltage to be applied;between the conductors 9 and 23,,- current flows through thiscapacitance and "through the con-1 ductor 2| to the wall of thememberadjacent.

the element 11, thence through the wallto'thi conductor 9. The flow ofcurrent through the; conductor 2| induces a voltage between the lowerf'end of the member l5 and the upper endat the. point of connection ofthe. radiator It, causing. current to flow in fromthe radiator 18 while;current is flowing out on the radiator '11, and vice versa. v I H Theslots l 9 are somewhat less than one-quar ter wavelength long, The twoportions of the ductive reactance between the slots I 9 and thecapacitive reactance of the conductors H and I8.

Although the invention has been described with re'ferefice'to a specifictype of radiator structure, it is "be'j understood that any type orradiator may. employed-"subject only to the limitation that pairs oflayers of four radiators equally spaced around acircular conductivesupport are used, withsthradiators of one layer displaced horizontally45 with respect to those of the other layers. Thisarrangement provides adirective pattern which isuniform throughout the horizontal plane,providing'the diameter of the circular support is substantially .6 andthe radiators are Ward from the Surface/10f. the conductor Th spacedsubstantially A from the urface of-the support; The above dimensions maybe changed throig hou-t a'limited :range without serious distortionotthe-desired circular pattern.

I claim as my invention:

1. An antenna system comprising a vertical conductive support andatleast one pair of-horizontallayers of 'radiator elements, each layercomprising four" elements spaced' radially from said support anddisposed at equal horizontal intervals-around said support; with theelements of 'onelayer "of each pair staggered horizontally byan'angle-ofv with-respect to those of the other layer of said pair meansinterconnecting saidsel'ements. so that the currents in all of said 3 5.elements-in allot said"layers are in time phase withreach other:

2;- An-antenna system comprising a cylindrical conductive Verticalsupport and a' plurality 'of horizontal layers of radiator-elements,each layer comprising four elements spacedradially from saidsupport:anddisposed at equal intervals around said support; with-the elements ofeach layer staggered; horizontally by an angle 'of 45 with 're'specttothose" of each adjacent layer layer of'each pair"displacedhorizontally45 with 1 respect to the corresponding elements of the other layerofsa-id pair means interconnecting said elementsso that'the currents inall of said elements in all of said layers are in time phase with eachother;-

4. A11 antenna-"system comprising a cylindrical conductiveverticalsupport and at least one pair of horizontal layers of radiatorelements, each layer comprisingfour elements spaced radially from saidsupportand'disposedat 90 intervals aroundfsaid-"support, with theelements of. one

layer "of each pain-displaced horizontally 45 \m'th re's'pectto thecorresponding elements of the other layereofwsaidpair' meansinterconnecting saidelehreiits so that she-currents in all of saidconductor 15 separated by the slots l9 function:rm elementsrirtrallffsaid layers are in time phase as a transmissiondine. shorted-atitslower end; providing an inductive reactancebetweenthe inner ends of themembers i! and IB. The members l1 and H) are each somewhatless thanoner-i,

with 'eachother:

.5.-r An antennasystem'comprising a hollow cylindricalvertical:conductorsubstantially .6 wavelengthzin' diaineterat the :frequency at which thequarter wavelength long, providing a capacitive systemrsis.stofnpirate,:atleast: one. zpairiof. horizontal layers, spaced vertically apartsubstantially one-half wavelength, of radiator elements, each layercomprising four elements disposed at 90 intervals horizontally aroundsaid support and substantially one-quarter wavelength distant radiallyfrom the surface of said support, with the elements of one layer of eachpair displaced horizontally 45 with respect to the correspondingelements of the other layer of said pair, conductor means extendingcoaxially within said hollow conductor, and means for coupling theradiator elements of each of said layers to said conductors atsubstantially one-half wavelength intervals thereon, whereby all of saidradiator elements are eifectively connected in parallel for operation inphase.

6. The invention as set forth in claim 5, wherein each of said radiatorelements includes a horizontally disposed linear conductor.

7. The invention as set forth in claim 5, wherein each of said radiatorelements comprises a horizontal dipole and the dipoles of each layer areorthogonally disposed with respect to each other.

8. The invention as set forth in claim 5, wherein each of said radiatorelements comprises a dipole.

9. An antenna system comprising a hollow vertical conductor, at leastone pair of horizontal layers, spaced vertically apart substantiallyonehalf wavelength, of radiator elements, each layer comprising fourelements disposed at 90 intervals horizontally around said support withthe elements of one layer of each pair displaced horizontally 45 withrespect to the corresponding elements of the other layer of said pair,conductor means extending coaxially within said hollow conductor, andmeans for coupling the radiator elements of each of said layerscophasally to said conductors the connections of each layer beingreversed with respect to those of the adjacent layers to providecophasal operation of all of said radiator elements.

10. An antenna system comprising a cylindrical vertical conductorsubstantially .6 wavelength in diameter at the frequency at which thesystem is to operate, at least one pair of horizontal layers of radiatorelements, each layer comprising four elements disposed at 90 intervalshorizontally around said support and substantially one-quarterwavelength distant radially from the surface of said support, with theelements of one layer of each pair displaced horizontally with respectto the corresponding elements of the other layer of said pair,

11. An antenna system comprising a vertical conductor, at least one pairof horizontal layers of radiator elements spaced vertically apart, eachlayer comprising four elements spaced radially from said support anddisposed at intervals horizontally around said support with the elementsof one layer of each pair displaced horizontally 45 with respect to thecorresponding elements of the other layer of said pair, and meansinterconnecting all of said radiator elements so that the currents inall of said elements in all of said layers are in time phase with eachother.

OAKLEY M. WOODWARD, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,086,976 Brown July 13, 19372,190,816 Wheeler Feb. 20, 1940 2,199,635 Koch May 7, 194.0 2,238,904Lindenblad Apr. 22, 1941 2,298,449 Bailey Oct. 13, 1942 2,338,564 AramJan. 4, 1944

